Trocar and cannula for veterinary use

ABSTRACT

A veterinary instrument having a trocar with a curved end and a cannula with its end curved to lie within the trocar during insertion, the cannula being rotatable with respect to the trocar to open out the curved ends after insertion and thereby lock the instrument in position. The parts are held in the closed and open conditions by a pin and slot connection and a biassing spring. A disc can be adjusted to bear against the animal&#39;&#39;s skin and thus secure the instrument more firmly.

I United States Patent [1113,570,498 72] inventor Charles Weighton [56] References Cited 64, Nettleham Road, Lincoln, England UNITED STATES PATENTS [21] P 1,798,124 3/1931 l-lunn 128/20 [22] 2 779 335 1/1957 n 128/347 45 Patented Mar. 16 1971 2,790,442 4/1957 Donaldson 128/348 [32] Priorlty Sept. 9, 1966 FOREIGN PATENTS [33] Great Britain 31 4044 69,722 8/1949 Denmark 128/347 Continuation of application Primary Examiner-Dalton L. Truluck 6 g 1967' now abandoned' Attorney-Roberts, Cushman and Grover ABSTRACT: A veterinary instrument having a trocar with a [54] if- W? FOR VETERINARY USE 22999 sa and 9 92999 49 itasai msd F999 ith u 5 .9 .9!" 9 995-19992999299 995195 1959995, e tab t [52] 0.8. CI. 128/347, respect to the trocar to open out the curved ends after inser- 128/20 tion and thereby lock the instrument in position. The parts are [51] Int. Cl. A61b 17/34 held in the closed and open conditions by a pin and slot con- [50] Field of Search 128/347- nection and a biassing spring. A disc can be adjusted to bear -351, 341343, 356, 303, 328, 20, 214.4, 215, against the animals skin and thus secure the instrument more 221 1 firmly.

, 1 TROCAR'AND CANNULA FOR VETERINARY USE This application is a continuation of Ser. No. 662,617 filed Aug. 23, 1967, now abandoned.

The invention relates to a trocar and cannula for veterinary use.

A cannula is a tube which may be inserted into the rumen of an ox to release trapped air -or other fluid. The insertion is made through the abdominal wall of the ox with the aid of a trocar, a sharp, pointed instrument. The cannula may be a straight tube in which the trocar is placed, during insertion, so as to project from the end of the cannula by say, half an inch. After insertion the trocar is removed to release the trapped air or other fluid. When it is desired to leave the cannula in position for some time then it may be attached to the animal's skin by means of adhesive applied to a flange projecting from the cannula. In such an arrangement the cannula may be loosened by movement of the animals body so that it may come partially out of the body.

According to the present invention there is provided a veterinary instrument comprising a cannula having a straight portion and a curved end portion, and a trocar having a tubular portion within which the straight portion of the cannula is rotatably received and an end portion which fits over one side of the curved end portion of the cannula and has a pointed tip,

the cannula being rotatable to a position in which its curved and trocar against relative rotation in either of two positions, in one of which the end portion of the trocar fits over the cannula and in the other of which the end portions are at an angle to one another. The cannula and trocar may be held in the locked positions by a spring against which they can be axially displaced for rotation of one relative to the other.

The instrument may also include a disc displaceable along the trocar to assist the anchorage of the instrument. After insertion of the trocar and rotation of the cannula to anchor the instrument within the rumen the disc is advanced to press against the skin of the animal and hold the instrument in place.

An embodiment of the invention will be described with reference to the accompanying drawings, in which:

FIG. 1 is a view of an instrument constructed according to the invention in the position occupied during insertion, the closed position.

FIG. 2 is a view of the instrument shown in FIG. 1 in the position occupied after insertion, the open position.

The instrument includes a cannula which, as shown in F IG. 1 is an open tube 1 having a straight portion and a curved end portion. When inserted through the side of an ox, into its rumen, collected fluid may enter the cannula by way of a hole 2 and leave by way of the outer end 3. A trocar is formed by a tubular element 4 which fits over the straight portion of the cannula and has an end portion 5 which fits over the inside of the curved end of the cannula and a pointed tip 6.

A knob 7 is fixed to the outer end of the cannula. The knob is pressed outwardly with respect to the trocar by a spring 8 and the outward motion is limited by a pin 9 projecting from the cannula and guided in a slot 10 in the trocar.

The instrument can be locked with the pin in two positions at the opposite ends of the slot and preferably at to each other.

One'locked position, the closed position is shown in F l6. 1. With the end of the cannula resting against the trocar, the instrument is inserted in the animal's side with a short stab. The knob 7 is then pressed to release the cannula which is then rotated to the other locked position, the open position, shown in FIG. 2.. This provides an anchorage preventing the withdrawal of the instrument until the lock is released. A movable disc 11 is mounted on the trocar and, after insertion of the instrument, is pressed on to the side of the animal and held by the fastening of a thumbscrew 12. This disc supplements the anchorage by firmly holding the instrument in position, with the end portions of the trocar resting against the internal wall of the rumen.

In the embodiment descrlbed, the trocar rests on the inner side of the curve of the cannula. In an alternative embodiment the trocar may rest on the outer side of the curve. In the latter case the spring would act in the opposite direction so as to retain the end of the cannula against the trocar in the 'closed' locked position.

I claim: 1. A veterinary instrument comprising: a cannula having a tubular straight portion and a tubular curved end portion;

a trocar having a tubular portion within which the tubular .straight portion of said cannula is rotatably received and a curved end portion having a concave inner surface adapted to fit over one side of the curved end portion of said cannula, said end portion having a pointed tip;

means for rotating said cannula between a first position in which its curved end portion is fitted within the curved end portion of said trocar and a second position in which its curved end portion is outside of and at an angle to the curved end portion of said trocar whereby said instrument may be anchored in position after insertion; and

an opening in the sidewall of said cannula substantially in alignment with the straight portion of said cannula.

2. An instrument as claimed in claim 1 including means for locking said cannula and trocar against relative rotation in either of said two positions.

3. An instrument as claimed in claim 2 comprising spring means for holding said cannula and trocar in the locked positions.

4. An instrument as claimed in claim 3 including a pin and slot connection between said cannula and said trocar, said slot having angularly spaced locking portions.

5. An instrument as claimed in claim 1 including a disc displaceable along said trocar to assist the anchorage of the instrument. 

1. A veterinary instrument comprising: a cannula having a tubular straight portion and a tubular curved end portion; a trocar having a tubular portion within which the tubular straight portion of said cannula is rotatably received and a curved end portion having a concave inner surface adapted to fit over one side of the curved end portion of said cannula, said end portion having a pointed tip; means for rotating said cannula between a first position in which its curved end portion is fitted within the curved end portion of said trocar and a second position in which its curved end portion is outside of and at an angle to the curved end portion of said trocar whereby said instrument may be anchored in position after insertion; and an opening in the sidewall of said cannula substantially in alignment with the straight portion of said cannula.
 2. An instrument as claimed in claim 1 including means for locking said cannula and trocar against relative rotation in either of said two positions.
 3. An instrument as claimed in claim 2 comprising spring means for holding said cannula and trocar in the locked positions.
 4. An instrument as claimed in claim 3 including a pin and slot connection between said cannula and said trocar, said slot having angularly spaced locking portions.
 5. An instrument as claimed in claim 1 including a disc displaceable along said trocar to assist the anchorage of the instrument. 